1. Field of the Invention
This invention relates to sealing cavities, and more particularly to systems and methods for properly sealing an air plenum box in a liquid treatment facility through inducement of a positive air pressure within the air plenum box.
2. Description of the Related Art
Municipal wastewater generally includes liquid-carried waste from bathrooms and sewers, as well as wastewater from building drains, storm drains, and the like. Untreated wastewater generally contains high levels of organic materials, pathogenic microorganisms, as well as other potentially toxic compounds. It thus entails environmental health hazards and consequently, must be conveyed from its generation sources and be treated appropriately before final disposal. In most instances, wastewater cannot be disposed of until the contaminants have been reduced to an acceptable level to governmental organizations, such as the United States Environmental Protection Agency.
The process of treating wastewater to an acceptable level involve subjecting the wastewater to a variety of physical, chemical, and biological processes. After most of the major contaminants, such as settable solids, have been filtered out by a wastewater treatment facility, the resulting wastewater often travels down to an aeration basin where the wastewater is further subjected to a relatively long-term exposure to bacteria and other microorganisms. The bacteria and microorganisms help remove the contaminants in the wastewater by quickly eating away or otherwise reducing the harmful contaminants so that the contaminants are substantially removed from the wastewater. In order for the bacteria and microorganisms to thrive and be able to remove the contaminants from the wastewater, they must have high levels of oxygen. Thus, it is important to enrich the often low-levels of oxygen in the wastewater by the use of an aeration system in a wastewater treatment facility.
The amount of oxygen is wastewater is conventionally measured in milligrams per liter. The initial wastewater before any physical, chemical, and biological processes by the water treatment facility may have no more than a few tenths of milligrams/liter of oxygen. After proper aeration methods, using submerged diffusers in the tanks containing the wastewater, the oxygen concentration may rise to five or six milligrams/liter which is appropriate to sustain life for the bacteria and other microorganisms.
An aeration basin in a wastewater treatment facility may span many hundreds of feet while the depth of the basin may be from ten to fifteen feet high. The quantity of air needed to aerate the wastewater varies from 0.005 to 2.0 cubic feet of air per gallon of wastewater in an aeration basin. An aeration basin, for example, comprises a series of eight parallel aeration tanks that receives wastewater, and at the bottom of each of the eight parallel aeration tanks, there exists a concrete air plenum box. Each air plenum box is generally independent and isolated from the other air plenum boxes. The top of each air plenum box is populated with a multitude of special diffuser lids. These diffuser lids have numerous small openings (known as pores) through which high pressure air flows into the wastewater in the aeration tank, thus oxygenating and agitating the wastewater.
In this process, the high pressure air often creates or expands cracks on the concrete base slab, and the perimeter of the air plenum boxes, allowing the air to escape through the cracks. More specifically, the high pressure air escapes through the cracks and into the surrounding air plenum boxes and other related facilities. As a consequence, the pressurize air may damage the surrounding air plenum boxes, but more importantly, less oxygen may be delivered to the wastewater. Over time, the cracks in the concrete's surface may become worse causing a structural malfunction in the air plenum box.
A conventional method to seal the cracks within an air plenum box involve spraying a sealant onto the interior surface of the air plenum box at atmospheric pressure. However, a problem with the conventional method is that the air plenum box is often improperly sealed before applying the sealant. This improper sealing of the box allows the air leaking from the adjacent tanks to bleed through the cracks in the air plenum box being sealed. This air leakage thereby makes the topical application of the sealant less effective as the air traveling inward displaces the sealant before the sealant thickens or cures in the cracks. Thus, leaking air from adjacent facilities often inhibits the effective sealing of cracks in the air plenum box.
Hence, it will be appreciated that there is a need for improved systems and methods for sealing an air plenum box or similar structure. To this end, there is also a need for a system and method for sealing air plenum boxes that seals cracks that are receiving inward air pressure from outside the air plenum box.